This invention relates to an improvement in a gas absorption process, in particular, a process wherein synthesis gases are scrubbed with a regenerable physical solvent to remove carbon dioxide, hydrogen sulfide, and metal carbonyls, and wherein metallic sulfide deposits foul, plug or clog the involved apparatus.
It is well known that apparatuses are fouled by metallic sulfides formed during the processing of synthesis gases produced by gasification of solid or liquid fuels with steam and oxygen under pressure and elevated temperatures, which gases are further refined into H.sub.2 --CO-synthesis gases. As has been previously determined, the fouling problem is caused by metal carbonyls contained in the synthesis gases and which tend to form sulfides with the sulfur compounds also present therein. These metallic sulfides are deposited on parts of the apparatus, such as heat exchangers or the regenerating column, resulting in a reduction in efficiency of each apparatus and the eventual plugging of same.
To avoid such plugging, it is taught in U.S. Pat. No. 4,144,314 issued March 13, 1979 to Doerges et al to add to the solvent certain complex-forming agents in a concentration of 0.005-1 g/l, said complexing agent being ethylenediaminetetraacetic acid, nitriloacetic acid, organic phosphonic acids and/or their derivatives, or their dissolved ammonium compounds. However, this technique has proven to exhibit less than the desired effectiveness for the elimination of plugging.